1. Field of the Invention
This invention relates to DRAM (dynamic random access memory) modules, and more particularly, to a preburn-in DRAM module circuit board which is directly connectable to a burn-in oven for performing a burn-in process concurrently on a plurality of DRAM modules mounted thereon.
2. Description of Related Art
FIG. 1 shows a conventional DRAM module circuit board which is mounted with an array of DRAM modules 100 thereon. Each of these DRAM modules 100 can be cut apart from the circuit board to function as a single memory unit. This conventional DRAM module circuit board is not provided with a burn-in circuit, so that the burn-in process for the DRAM modules 100 on the circuit board is performed for the DRAM modules 100 after they are cut apart from the circuit board.
Most conventional DRAM modules are manufactured by the following procedural steps: (1) wafer sorting, which is also called chip-probe (CP) testing; (2) IC package assembly; (3) final testing-1; (4) burn-in; (5) final testing-2; (6) module assembly; (7) module testing; and (8) shipping.
Some low-end DRAM modules are manufactured by a simplified procedure which includes the following steps: (1) wafer sorting (CP testing), (2) IC package assembly or chip-on-board, (3) module assembly, (4) module system burn-in, (5) module testing, and (6) shipping.
Conventional manufacturing processes for DRAM modules have some drawbacks. First, the procedure is quite complex and time-consuming to complete. Second, the burn-in and module warm-up should be separately carried out, each process requiring one or two days to complete, which is quite inconvenient and time-consuming. Third, the circuit board used for the burn-in process and that used for constructing the DRAM modules are separate ones, which means that the DRAM modules should be cut apart from the DRAM module circuit board and then mounted on a burn-in circuit board to undergo the burn-in process. The work involved is thus quite laborious and cost-ineffective. Fourth, the module warm-up process is applicable to one module only at a time, which is quite inefficient. Fifth, in the module warm-up process, the voltage and current can not be s suitably controlled, which can cause degradation to the IC quality and reliability.